Manufacture of tungsten filaments for incandescent electric lamps.



ROOM

UNITED STATES PATEN OFFICE.

ANTON LEDERER, or mil-m, AUSTRIA-HUNGARY, AS-SIGNOR 'ro WESTINGHOUSE LAMP COMPANY, A CORPORATION OF PENNSYLVANIA.

MANUFACTURE OF TUNGSTEN FILAM ENTS FOR INCANDESCENT ELECTRIC LAMPS.

No Drawing.

, Specification of Letters Patent.

To all whom it may concern:

Be it known that I, ANTON subject of the Emperor of Austria-Hungary,

and a resident of Vienna, Austria-Hungary,

1 isinglass, levulose, etc., in such proportions .that the whole of the carbon of the binding material may be removed by the oxygen of the tungsten dioxid. From this mass filaments are squirted which are then heated in theabsence of oxidizing gases,so that the carbon is removed and me tungsten filaments obtained. I have ound from experience thatsuch filaments only become sufliciently strong for further manipulation when the heating is conducted at a-temperature considerably in excess of the temperature necessary for reduction.

The object of the present invention is to obviate heating the filaments at this stage to, an excessive'tem'perature, and I have found that by adding powdered metallic tungsten to the paste of tungsten dioxid and binding material, the filament is sufiiciently strong for the later manipulations without it being necessary to heat to a temperature exceed ing that at which the reduction takes place.- n accordance withmy invention a suitable quantity of powdered tungsten metal is addedto the pasteconsisting of tungsten dioxid and carbonaceous binding material.

This aste is then squirted through dies and the laments obtained are heated to the temperature necessary for the reduction of the tungsten dioxid. This temperature is amply suflicient to give the filaments the strength necessary for the further manipulation. The addition of tungsten metal to the paste does not in any way influence the reaction described in my previous specifica-* tion above mentioned by means of which the carbon is removed because only. the carbon of the binding agent and the oxygen of the tungsten dioxid take part in the reaction.

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This reaction may be conveniently expressed by the following equation Since the agglutinants mentioned in the opening paragraph of the specification pos- Patented J 111 30, 1912;

Application filed June 8, 1909. 1 Serial No. 500,955.-

sess great binding qualities, the process hcres 1n '(lQSCI'lbQClCtID be easily carried out.al-

though a smaller proportion of agglutinant is employed. I have in fact discovered that incertain circumstances particularly when manufacturing filaments of large cross sect1on,,wh1ch smter together lesseasily it is advantageous to take a smaller quantity of binding agentthan is necessary for'the com-. plete reduction of the tungsten dioxid used, and in' order to effect a complete reduction of the oxid it is then necessary to make up the deficiency by adding to the mixture a sufiicient quantity of pure carbon, for instance graphite, lamp-black or. soot. It is of course obvious that in such cases care must be taken when making an addition of pure carbon to have a sufficient quantity of 1 tungsten dioxid in the paste to supply the necessary amount of oxygen to oxidize all the carbon. The filaments thus obtained arethen heated to incandescence in a suitable environment by passage through them ofan electric current for the 'purpose of completing the reduction of any oxid they may still contain and forsintering them.

I claimas my invention: I

1. The process of manufacturing homogleneous tungsten filaments for incandescent e ectrlc a paste of tungsten dioxid and a suitable carbonaceous binding material in such proportions-that the carbon of the binding. material is approximately suflicient to combine with the oxygen of the tungsten dioxid, incorporating powdered tungsten metal with the paste for the purpose of facilitating the reduction of the tungsten dioxid by the carbon of the binding'material, squirting said paste into filaments, dryin ing said filaments in the a sence of 0x1d1zing gases to the tem reduction and therea er finishin the metal filaments roduced in a suitab e manner, substantially as described. 2. The process of manufacturing homogeneous tungsten filaments for incandescent electric lamps which consists in preparing a lamps-which consists in preparing the same, heat- 1 rature necessary for paste of tungstendioxid and a suitable carbonaceous binding material in such proportions that the carbon of the binding material is approximately suflicient to combine with the oxygen of the tungsten dioxid, incorporating powdered tungsten metal with the paste for the purpose of facilitating the reduction of the tungsten dioxidby the carbon of the binding material, squirting said aste into filaments, dryin the same, heatmg said 'filamentsin the a sence of oxidizin gases to the temperature necessary for re uction' and heating said filaments to incandescence by passage therethrough of an electric current in a suitable environment, substantially as described.

3. The process of manufacturing homogeneous tungsten filaments for incandescent electric lamps which consists in preparing a paste of tungsten dioxid and a suitable caronaceous binding material and carbon in such proportions that the total carbon is approximately suflicient to combine with the oxygen of the tungsten dioxid, incorporating powdered tun sten 'metal with the paste for the purpose 0 facilitating. the reduction of the tungsten dioxid by the carbon of the binding material, squirting-said paste into filaments, drying the same, heating said filaments in the absence of oxidizing gases to the temperature necessary for reduction and heating said'filaments to incandescenoe by passage therethrough of an electric current in a suitable environment, substantially as described.

In testimony whereof I have hereunto subscribed my name this 3rd day of June 1909.

ANTON LEDERER.

Witnesses:

CHARLES A. TERRY, WM. H. CAPEL. 

